org.apache.flink.graph

Class AnalyticHelper<T>

java.lang.Object

org.apache.flink.api.common.io.RichOutputFormat<T>

org.apache.flink.graph.AnalyticHelper<T>

Type Parameters:

T - element type

All Implemented Interfaces:

Serializable, OutputFormat<T>

public abstract class AnalyticHelper<T>
extends RichOutputFormat<T>

A GraphAnalytic computes over a DataSet and returns the results via Flink accumulators. This computation is cheaply performed in a terminating RichOutputFormat.

This class simplifies the creation of analytic helpers by providing pass-through methods for adding and getting accumulators. Each accumulator name is prefixed with a random string since Flink accumulators share a per-job global namespace. This class also provides empty implementations of OutputFormat.open(int, int) and OutputFormat.close().

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AnalyticHelper()

Method Summary

Modifier and Type	Method and Description
<V,A extends Serializable> void	addAccumulator(String name, Accumulator<V,A> accumulator) Adds an accumulator by prepending the given name with a random string.
void	configure(Configuration parameters) Configures this output format.
<A> A	getAccumulator(ExecutionEnvironment env, String accumulatorName) Gets the accumulator with the given name.
void	open(int taskNumber, int numTasks) Opens a parallel instance of the output format to store the result of its parallel instance.

Methods inherited from class org.apache.flink.api.common.io.RichOutputFormat

getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.flink.api.common.io.OutputFormat

close, writeRecord

Constructor Detail

AnalyticHelper

public AnalyticHelper()

Method Detail

configure

public void configure(Configuration parameters)

Description copied from interface: OutputFormat

Configures this output format. Since output formats are instantiated generically and hence parameterless, this method is the place where the output formats set their basic fields based on configuration values.

This method is always called first on a newly instantiated output format.

Parameters:

parameters - The configuration with all parameters.

open

public void open(int taskNumber,
                 int numTasks)
          throws IOException

Description copied from interface: OutputFormat

Opens a parallel instance of the output format to store the result of its parallel instance.

When this method is called, the output format it guaranteed to be configured.

Parameters:

taskNumber - The number of the parallel instance.

numTasks - The number of parallel tasks.

Throws:

IOException - Thrown, if the output could not be opened due to an I/O problem.

addAccumulator

public <V,A extends Serializable> void addAccumulator(String name,
                                                      Accumulator<V,A> accumulator)

Adds an accumulator by prepending the given name with a random string.

Type Parameters:

V - Type of values that are added to the accumulator

A - Type of the accumulator result as it will be reported to the client

Parameters:

name - The name of the accumulator

accumulator - The accumulator

getAccumulator

public <A> A getAccumulator(ExecutionEnvironment env,
                            String accumulatorName)

Gets the accumulator with the given name. Returns null, if no accumulator with that name was produced.

Type Parameters:

A - The generic type of the accumulator value

Parameters:

accumulatorName - The name of the accumulator

Returns:

The value of the accumulator with the given name